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From: Shakeel Butt To: Qi Zheng Cc: hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, muchun.song@linux.dev, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chenridong@huaweicloud.com, mkoutny@suse.com, akpm@linux-foundation.org, hamzamahfooz@linux.microsoft.com, apais@linux.microsoft.com, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: Re: [PATCH v2 21/28] mm: swap: prevent lruvec release in lru_gen_clear_refs() Message-ID: <6as6jdgqy4vrq2skolwnqzef2n7xljpw7yul6vm6g3k5pbzd2k@vluyqctcvxj5> References: <42682f81686e31019504a6e025fa08d2c9dea718.1765956026.git.zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42682f81686e31019504a6e025fa08d2c9dea718.1765956026.git.zhengqi.arch@bytedance.com> X-Migadu-Flow: FLOW_OUT X-Stat-Signature: eqkquxtrotb55y7jz74u1krkwwugqxx7 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 1A36A8000D X-Rspam-User: X-HE-Tag: 1766193908-669764 X-HE-Meta: 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 0NKdKvig xNhsetvEB4ptjhnrIyOildJM3M9GPbYoC8iZKdjvBONhEDtuWz9G0MGmGoHF2IUjduqeRWxHnRYt6YAxKYG0VNiiJvfo8He/hzWn8Xepxc+RhiQywpEWVVsLnCBHhYUpGGKxxtP7K+OoTAAfHpk3et2WKyx/mQ85Ze3CtEjoj7xz5HR/2oiAr37WoR5eiYaw+7jm/C9nPPfmPIydJBUzLmcjqnby7f1NAKZ8z1cDyJSBGTNbY6reRLf+SOqlrjSt1u8VXbK3aXpil9f3KxfktYcSKjxa9RajGRYnTLMY2KR0RBas= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Dec 17, 2025 at 03:27:45PM +0800, Qi Zheng wrote: > From: Muchun Song > > In the near future, a folio will no longer pin its corresponding > memory cgroup. So an lruvec returned by folio_lruvec() could be > released without the rcu read lock or a reference to its memory > cgroup. > > In the current patch, the rcu read lock is employed to safeguard > against the release of the lruvec in lru_gen_clear_refs(). > > This serves as a preparatory measure for the reparenting of the > LRU pages. > > Signed-off-by: Muchun Song > Signed-off-by: Qi Zheng > Reviewed-by: Harry Yoo Acked-by: Shakeel Butt